Front end is pretty nice, decent functionality overall. Back end is not well-coded. There's a fixed dependency on a single server (non-CDN). If this server is down, the two script-loading calls fail, completely halting all other scripts from executing. Why not async? Why not error-trap? Why not copy and let host locally?
To add insult, when this server is down, you also can't disable the plug-in. Your site and its users will be stuck in this dysfunctional mode until the devs restore the services. Even if you uninstall the plug-in altogether, the script-loading directives are still present, causing your site to continue to lag and fail.